Alez
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| posted on 10/10/07 at 02:24 PM |
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High power alternator for V8?
Hi All,
I've been having slight cooling problems with the Fury V8. As a result, I changed the fans it had for twin high performance ones. Because of
this, now the alternator can't cope (as the fans need to run most of the time presently): it still charges the battery but only when the engine
is at sustained high rpm.
I need to replace it with one similar in size as the bonnet is close, but high current / power (fans alone are 2 x 13A). I don't know what the
current alternator is or where to look for a suitable replacement. I'm happy to use a scrapyard alternator or order any brand new OEM high
performance one (just as I did for the fans, which now are expensive Pacet ones) if that's my best bet.
A few pics of the current alternator (which charges great with fans off) should follow this post.
Thanks very much for any comments.
Alex
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Alez
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| posted on 10/10/07 at 02:25 PM |
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Alez
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| posted on 10/10/07 at 02:25 PM |
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Rescued attachment alternator2.jpg
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Alez
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| posted on 10/10/07 at 02:26 PM |
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Rescued attachment alternator3.jpg
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Alez
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| posted on 10/10/07 at 02:29 PM |
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Rescued attachment alternator6.jpg
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Agriv8
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| posted on 10/10/07 at 02:37 PM |
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Alez,
Are there any marking on it as one of these should tell you how many Amps it is kicking out at the moment.
I would say it looks like a modern one so suspect it should be ciking out around 50 to 60 amps maybe someone could post up how to test what Ampage it
is clicking out.
Regards
Agriv8
Taller than your average Guy !
Management is like a tree of monkeys. - Those at the top look down and see a tree full of smiling faces. BUT Those at the bottom look up and see a
tree full of a*seholes .............
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02GF74
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| posted on 10/10/07 at 03:12 PM |
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that is small - looks like the kubota one, from memory they throw out either 45 or 55 A but not sure at what rpm; you certainly won't see that
at idle.
As I am sure you know, you can get bracket to fit alternator on either side of engine so it there more room on other side?
Early Range Rover ones, Lucas A 127 come in flavours of 65 A , 75 and 85 A but they are bigger than your tidler.
I thihnk the real issue is cooling - you need to look at how better to trtasnfer heat from the eingine -> water -> radieotr -> air.
you tried water wetter?
deeper/larger radiator?
vents?
cowling to direct air in and out of radiator?
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Paul (Notts)
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| posted on 10/10/07 at 03:14 PM |
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I have just fitted a heavy duty kenlow fan to my v8 ( 14 inch two speed type -at max speed takes around 25 amps. )and the current alternator is only
just up to the job ( at idle ) - its a 60 amp type.
I was looking at changing it for a 70 amp or 100 amp from RPI soon.
http://cgi.ebay.co.uk/Land-Range-Rover-V8-Engine-Alternator-Morgan-90-110_W0QQitemZ320168357585QQihZ011QQcategoryZ31349QQtcZphotoQQcmdZViewItem
seems a fair price to me.
Paul
( just watch where the connecting lugs are on your replacment type so that they match the one you have. )
[Edited on 10/10/07 by Paul (Notts)]
[Edited on 10/10/07 by Paul (Notts)]
[Edited on 10/10/07 by Paul (Notts)]
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VinceGledhill
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| posted on 10/10/07 at 03:36 PM |
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Seems to me that your pully is too large. The alternators aren't going fast enough at idle.
2 x 13 amps = 26 amps. Running engine with nothing else on = 27 amp alternator is big enough.
Alternators outputs are plenty for your kit car.
Engine that this alternator was OEM for may rev higher than your rover.
Try having a look round the scrap yard for a smaller pulley to fit your alternator.
5 euros... job done.
Why would you need a 100A alternator? Just make it run faster at idle by changing the pulley for a smaller one.
[Edited on 10/10/07 by VinceGledhill]
[Edited on 10/10/07 by VinceGledhill]
Regards
Vince Gledhill
Time Served Auto Electrician
Lucas Leeds 1979-1983
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02GF74
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| posted on 10/10/07 at 04:57 PM |
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quote:
Originally posted by VinceGledhill
Why would you need a 100A alternator? Just make it run faster at idle by changing the pulley for a smaller one.
a lot of v8 originate from Range Rovers which aren't exactly the high revvers - nor do they go to the redline; performance engine would are more
likle to see both so you should work out the size of pulley needed, bearing in mind max speed of alternators is around 12,000 rpm.
I dare say you can go above that but how mcuh before damage (mechanical) will occur?
the battery should supply the juice at low rpm and be recharged once you are on the move.
as I said ^^^, I don't think this is the ideal solution to curing overheating.
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Alez
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| posted on 10/10/07 at 06:04 PM |
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Thank you all very much.
Agriv8, can't find any marks I'm afraid.
O2gf74, relocating it to the other side would make no difference as both sides have the same room presently. I agree that the real issue is cooling
and this is being looked at with a number of mods (it will be getting bigger radiator, smaller water pump pulley and vents in the bonnet) but still
I'd like a more powerful alternator just for peace of mind that I'll have a properly topped up battery after driving in town for
instance.
Vincegledhill, I'm not sure about the pulley being too large, the battery charges really well without fans or lights giving 14V as soon as you
are at say 1400 rpm. Either lights or fans result in higher rpms, say 2000, to reach 13V, 3000 for 14V. Both lights and fans result in 13V only when
cruising at steady 3000 rpm or higher. This means that a summer night out in town with the car would result in continuous discharge without any
replenishing at all. The engine is a Rover V8 so I tend to drive at low-ish rpm generally.
Paul, thanks for the pointer, I'd like to go for a big 100A guy to make sure I'm improving things (as it's not clear what the
current alternator gives) but I haven't found one from RPI. The choices seem to be:
http://cgi.ebay.co.uk/Land-Range-Rover-V8-Engine-Alternator-Morgan-90-10_W0QQitemZ320155642219QQihZ011QQ
That's the "buy now" for the model you provided:
Brand New Rover V8 Heavy Duty Replacement Alternator
Maximum output power is 1062 Watts
Maximum output under full load 85 Amps
Voltage Regulator set point 14.5 Volts
Turn on speed (indicator lamp out) 1933 RPM
Then there's:
http://cgi.ebay.co.uk/Land-Range-Rover-V8-Engine-Alternator-Morgan-TVR-MG-SD1_W0QQitemZ320168731415QQihZ011QQ
Brand New Lucas Alternator for Rover V8 Engine
Maximum output power is 935 Watts
Maximum output under full load 72 Amps
Voltage Regulator set point 14.37 Volts
Turn on speed (indicator lamp out) 1500 RPM
What do you think?
Any other comments in view of this? I'm still unsure about what to do.
Thanks.
Alex
[Edited on 10/10/07 by Alez]
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Alez
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| posted on 10/10/07 at 08:18 PM |
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OK, I think I got it from Vincegledhill and O2gf74 posts.. I measured pulley diameters.. the engine one is roughly 15.5 cm and the alternator one is 9
cm.
At 3000 rpm (good enough for the alternator to charge the battery a bit with lights and fans), the alternator is running at 3000 x 15.5 / 9 = 5170 rpm
(far from 12000).
If we want 12000 alternator rpm at 5000 engine rpm, pulley needed is 15.5 cm * 5 / 12 = 6.5 cm (rather smaller than the current one). Or should I go
for 12000 at 4500, what do you reckon?
With that fitted, what I'm now getting at 3000 rpm I would get at 3000 x 6.5 / 9 = 2170 rpm.
Looks like a fair improvement, although I've also checked clearance with the bonnet (again) and I think a bigger alternator would fit.
Cheers,
Alex
[Edited on 10/10/07 by Alez]
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02GF74
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| posted on 11/10/07 at 01:54 PM |
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if you can buy cheaply or make a smaller alternarro pulley then that it worth a shot but that is not best approach.
As the fans are running, you draw power from the alternator so engine works harder so it gets hooter so the fans need to run which draw power .....
etc.
have you measured radadiator temp?
is thermostat working?
what is opening temp of thermostat? (they some in 3 varieties)
where is radiator fan thermostat switch?
is id adjustable? (try setting it to 95 C)
do you have an air lock? If you are running twin SU or strombergs, the manifold has a small bleed tube - this should go to radiator.
have you tried water wetter?
are your exhaust manifold wrapped? (only done on mild steel ones).
what radiator are you using? is it in good condiiton (inside and out)?
can you fit one big fan? I did the sums for this a whicl back and found that the area swept by blades by on one big fan is bigger than two smaller
fans (the cnetre of the fan does not contribute to ari flow, just the blades).
How close is the fan to the radiators? fit a cowl to optimise air. & vents for it to go out.
what about fitting a smwller water pump puller to push the wager around faster? water pump impeloer wokring properly?
no kinked hoses?
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Alez
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| posted on 11/10/07 at 03:55 PM |
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Thanks O2gf74 (is that a car number plate or something?).
I understand what you mean. It's not bad as it is with either lights or fans, so I'll try to get a smaller pulley first and see how it
does.
Radiator temp not measured.
I don't have a thermostat as a cold engine is not a realistic scenario.
The fan thermostat isn't fitted yet, presently I have a switch in the dash, so fully adjustable 
A bleed tube has been added recently at the top of the circuit and seems to work well.
The circuit has some water wetter.
Exhausts mainfold fully wrapped.
I don't know what the radiator is but I'll fit a thicker and bigger one.
I may be able to fit one big fan instead but I'd rather not because the current ones were rather expensive.
The attachment of the fans to the radiator is not perfect.
Smaller water pump pulley on its way (delayed due to UK postal service strike!).
I'm also planning a few bonnet vents.
I didn't know that I should set the fan thermostat trig point as high as 95 degC. Currently I was switching the fans on at 90. If it's
cool outside and I can keep the car moving all the time (no traffic lights etc.), it stays at 90 without fans.
Cheers,
Alex
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